Valid Sudoku

Determine if a Sudoku is valid, according to: Sudoku Puzzles - The Rules.

The Sudoku board could be partially filled, where empty cells are filled with the character '.'.

A partially filled sudoku which is valid.

 

 1 public class Solution {

 2     public boolean isValidSudoku(char[][] board) {

 3         // Note: The Solution object is instantiated only once and is reused by each test case.

 4         if(board == null || board.length != 9 || board[0].length != 9) return false;

 5         int[] checkr = new int[9];

 6         int[] checkc = new int[9];

 7         for(int i = 0; i < 9; i ++){

 8             for(int j = 0; j < 9; j ++){

 9                 if(board[i][j] - '0' > 0 && board[i][j] - '0' < 10){

10                     checkr[board[i][j] - '0' - 1] ++;

11                 }

12                 if(board[j][i] - '0' > 0 && board[j][i] - '0' < 10){

13                     checkc[board[j][i] - '0' - 1] ++;

14                 }

15             }

16             for(int ii = 0; ii < 9; ii ++){

17                 if(checkr[ii] > 1 || checkc[ii] > 1){

18                     return false;

19                 }

20             }

21             checkr = new int[9];

22             checkc = new int[9];

23         }

24         for(int i = 0; i < 9; i ++){

25             for(int j = 0; j < 3; j ++){

26                 if(board[i][j] != '.')

27                     checkc[board[i][j] - '0' - 1] ++;

28             }

29             if((i + 1) % 3 == 0){

30                 for(int ii = 0; ii < 9; ii ++){

31                     if(checkr[ii] > 1 || checkc[ii] > 1){

32                         return false;

33                     }

34                 }

35                 checkc = new int[9];

36                 }

37             }

38         

39         checkc = new int[9];

40         for(int i = 0; i < 9; i ++){

41             for(int j = 3; j < 6; j ++){

42                 if(board[i][j] != '.')

43                     checkc[board[i][j] - '0' - 1] ++;

44             }

45             if((i + 1) % 3 == 0){

46                 for(int ii = 0; ii < 9; ii ++){

47                     if(checkr[ii] > 1 || checkc[ii] > 1){

48                         return false;

49                     }

50                 }

51                 checkc = new int[9];

52                 }

53             }

54         

55         checkc = new int[9];

56         for(int i = 0; i < 9; i ++){

57             for(int j = 6; j < 9; j ++){

58                 if(board[i][j] != '.')

59                     checkc[board[i][j] - '0' - 1] ++;

60             }

61             if((i + 1) % 3 == 0){

62                 for(int ii = 0; ii < 9; ii ++){

63                     if(checkr[ii] > 1 || checkc[ii] > 1){

64                         return false;

65                     }

66                 }

67                 checkc = new int[9];

68                 }

69             }

70         

71         return true;

72     }

73 }

 第二遍：

 1 public class Solution {

 2     public boolean isValidSudoku(char[][] board) {

 3         // Note: The Solution object is instantiated only once and is reused by each test case.

 4         if(board == null || board.length != 9 || board[0].length != 9) return false;

 5         boolean[] checkr = new boolean[9];

 6         boolean[] checkc = new boolean[9];

 7         for(int i = 0; i < 9; i ++){

 8             checkr = new boolean[9];

 9             checkc = new boolean[9];

10             for(int j = 0; j < 9; j ++){

11                 if ( board[i][j] != '.'){

12                     if(checkr[board[i][j] - '1']) return false;

13                     checkr[board[i][j] - '1'] = true;

14                 }

15                 if ( board[j][i] != '.'){

16                     if(checkc[board[j][i] - '1']) return false;

17                     checkc[board[j][i] - '1'] = true;

18                 }

19             }

20         }

21         for(int a = 0; a < 3; a ++){

22             for(int b = 0; b < 3; b ++){

23                 checkr = new boolean[9];

24                 for(int i = a * 3; i < (a + 1) * 3; i ++){

25                     for(int j = b * 3; j < (b + 1) *3; j ++){

26                         if ( board[i][j]!='.' ){

27                             if(checkr[board[i][j] - '1']) return false;

28                             checkr[board[i][j] - '1'] = true;

29                         }

30                     }

31                 }

32             }

33         }

34         return true;

35     }

36 }

 第三遍：

 1 public class Solution {

 2     public boolean isValidSudoku(char[][] board) {

 3         if(board == null || board.length != 9 || board[0].length != 9) return false;

 4         boolean[] value = new boolean[9];

 5         for(int i = 0; i < 9; i ++){

 6             value = new boolean[9];

 7             for(int j = 0; j < 9; j ++){

 8                 if(board[i][j] != '.' && value[board[i][j] - '1']) return false;

 9                 else if(board[i][j] != '.' && !value[board[i][j] - '1']) value[board[i][j] - '1'] = true;

10             }

11             value = new boolean[9];

12             for(int j = 0; j < 9; j ++){

13                 if(board[j][i] != '.' && value[board[j][i] - '1']) return false;

14                 else if(board[j][i] != '.' && !value[board[j][i] - '1']) value[board[j][i] - '1'] = true;

15             }

16         }

17         for(int k = 0; k < 3; k ++){

18             for(int h = 0; h < 3; h ++){

19                 value = new boolean[9];

20                 for(int i = 3*k; i < 3*k + 3; i ++){

21                     for(int j = 3*h; j < 3*h + 3; j ++){

22                         if(board[i][j] != '.' && value[board[i][j] - '1']) return false;

23                         else if(board[i][j] != '.' && !value[board[i][j] - '1']) value[board[i][j] - '1'] = true;

24                     }

25                 }

26             }

27         }

28         return true;

29     }

30 }